As far as I know , its only the 558/658 , that has the large plastic insert at the rear of the bolt for smooth cycling & less wobble etc , the later 595/695 does not have the palstic collar , also the 558 is round action , and the later 595 is square etc , so quite different .
So in short although they both use a 2 lung bolt thats similar , the actions are very different , ie round & square in profile